[release/10.0] Avoid referencing types of JsonIgnore'd properties. #120569
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Co-authored-by: Copilot <[email protected]>
This reverts commit ed3bcc3.
jeffhandley
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Oct 9, 2025
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Tagging subscribers to this area: @dotnet/area-system-text-json, @gregsdennis |
eiriktsarpalis
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Oct 9, 2025
stephentoub
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Oct 10, 2025
artl93
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Backport of #120543 to release/10.0
/cc @jeffhandley @eiriktsarpalis
Customer Impact
The Microsoft.Extensions.AI and Agent Framework libraries use
[Experimental]attributes on APIs related to emerging AI concepts. We have found that System.Text.Json source-generated serialization code results references members and types that result in diagnostics--[Experimental],[Obsolete], and other such attributes can cause that behavior. Because the references are in generated code, suppressions cannot be applied at the call site--leading to the need for project-wide suppressions.Project-wide suppressions on these diagnostics hide the fact that the customer is exposing non-stable APIs on their serialization model. Before this change, applying
[JsonIgnore]to the types or members does not eliminate all references to the annotated APIs in the source-generated code, which is an unexpected behavior, and this still leaves the customer needing to apply project-wide suppressions.With those project-wide suppressions in place, we cannot be confident that
[Experimental]API names/shapes can be changed without catching consumers by surprise.A customer encountered this issue while implementing a community contribution that involved the
[Experimental]attribute in add support for background responses (dotnet/extensions#6854).Fix
If the property is ignored and its type is not used anywhere else in the type graph, emit a
JsonPropertyInfoof type 'object' to avoid unnecessarily referencing the type. STJ requires that all ignored properties be included so that it can perform necessary run-time validations using configuration not known at compile time such as the property naming policy and case sensitivity.Regression
Testing
New tests were added to exercise the scenarios of where we expect diagnostics to be avoided, and testing was added to ensure diagnostics are still raised when an API is not marked as
[JsonIgnore]. The tests illustrate the end-to-end AI scenarios are unblocked.Risk
Medium. Any changes to System.Text.Json incur risk of affecting serialization, and changes to the source generator carry additional risk. These risks are mitigated by this being a very surgical fix that did not affect any existing tests.